Code
class ListItemTransferHandler extends TransferHandler {
@Override public int getSourceActions(JComponent c) {
System.out.println("getSourceActions");
if (!(c instanceof JList)) {
return TransferHandler.NONE;
}
JList<?> source = (JList<?>) c;
Point pt;
if (compact) {
int w = source.getFixedCellWidth();
int h = source.getFixedCellHeight() - 20; // TODO: 20 ???
setDragImage(createCompactDragImage(source, w, h));
pt = new Point(w / 2, h);
} else {
setDragImage(createDragImage(source));
pt = c.getMousePosition();
}
if (pt != null) {
setDragImageOffset(pt);
}
return TransferHandler.MOVE; // TransferHandler.COPY_OR_MOVE;
}
private static BufferedImage createDragImage(JList source) {
int w = source.getWidth();
int h = source.getHeight();
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics g = bi.getGraphics();
DefaultListCellRenderer renderer =
(DefaultListCellRenderer) source.getCellRenderer();
for (int i : source.getSelectedIndices()) {
Component c = renderer.getListCellRendererComponent(
source, source.getModel().getElementAt(i), i, false, false);
Rectangle rect = source.getCellBounds(i, i);
SwingUtilities.paintComponent(g, c, source, rect);
}
g.dispose();
return bi;
}
private BufferedImage createCompactDragImage(JList source, int w, int h) {
BufferedImage br = null;
if (w > 0 && h > 0) {
br = source.getGraphicsConfiguration().createCompatibleImage(
w, h, Transparency.TRANSLUCENT);
} else {
return null;
}
int[] selectedIndices = source.getSelectedIndices();
int length = selectedIndices.length;
Graphics g = br.getGraphics();
DefaultListCellRenderer renderer =
(DefaultListCellRenderer) source.getCellRenderer();
int idx = selectedIndices[0];
Object valueAt = source.getModel().getElementAt(idx);
Component c = renderer.getListCellRendererComponent(
source, valueAt, idx, false, false);
Rectangle rect = source.getCellBounds(idx, idx);
SwingUtilities.paintComponent(g, c, source, 0, 0, rect.width, rect.height);
if (length > 1) {
LABEL.setText(String.valueOf(length));
Dimension d = LABEL.getPreferredSize();
SwingUtilities.paintComponent(
g, LABEL, source, (w - d.width) / 2, (h - d.height) / 2, d.width, d.height);
}
g.dispose();
br.coerceData(true);
return br;
}
// ...
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